1. Field of the Invention
An embodiment of the invention relates generally to the field of data networking. More particularly, an embodiment of the invention relates to methods and apparatus for forward baseband digitalization.
2. Discussion of the Related Art
Prior art advanced broadband networks are known to those skilled in the art. For instance, a conventional advanced broadband network typically includes a headend, a number of hubs, and a larger number of nodes through which a still larger number of subscribers are serviced.
A problem with this technology has been related to the difficulty of achieving highly linear transmission over short and long fiber links at affordable cost. The technology commonly referred to as directly modulated 1310 nm analog lasers for 50 to 860 MHz bandwidth is distance limited to 40 km and loss budget limited to 15-18 dB and expensive at high output levels that allow for such distant locations to be reached. The technology commonly referred to as externally modulated 1550 nm optical analog transmitters for 50 to 860 MHz bandwidth is relatively very expensive for all distances and practically not applicable for distances in excess of 100 km. Therefore, what is required is solution that allows for much longer optical links at affordable cost and at the same or better performance.
Another problem with this technology has been that several links cascaded add cumulatively interference levels. Therefore, what is also required is a solution that allows for cascading OEO signal regenerators without signal degradation.
One unsatisfactory approach to overcoming this distance limitations involves, bandwidth splitting and using several separate transmitters to transmit much lower bandwidth, ideally within one frequency octave. However, a disadvantage of this approach is that it increases the cost of the link by the factor of two or higher. Another unsatisfactory approach for overcoming high loss budget with 1550 nm technology is to use optical amplification of the optical signal. However, a disadvantage of this approach is significant cost increase at low gains in loss budget and at measurable performance degradation. Therefore, what is also needed is a solution that meets the above-discussed requirements in a more cost-effective manner.
Heretofore, the requirements of long distance or high loss budget links at affordable cost without performance degradation, referred to above have not been fully met. What is needed is a solution that simultaneously meets all of these requirements.